State of the Water
Quality

The state of the water
quality was judged by comparing values to the Ministry of
Environment, Lands and Parks' Approved and Working Criteria for
Water Quality (Nagpal et al., 1995). The following 24 water
quality indicators were not discussed as they easily met all water
quality criteria and showed no clearly visible trends: arsenic,
barium, beryllium, carbon (total inorganic), chloride, cobalt,
lithium, magnesium, molybdenum, nitrate/nitrite, total dissolved
nitrogen, phosphorus, potassium, filterable residue, fixed
filterable residue, fixed non-filterable residue, selenium, silica,
sodium, specific conductance, strontium, sulphate and
vanadium.

Flow (Figure
2) values were highest during freshet (April-July). Peak flow values were
similar most years except for higher values in 1990 and 1992. Lower peak values
occurred in 1984, 1986, 1989 and 1991. Secondary peaks occurred in the fall
due to fall rains.

Total aluminum (Figure
4) values exceeded the 5 mg/L total aluminum criterion for wildlife and
livestock three times (spring 1993 and summer 1994). These periods of high
values corresponded with periods of high suspended sediments (non-filterable
residues and turbidity). This suggests that the aluminum was in a particulate
form and probably not biologically available. Dissolved aluminum should also
be measured to permit comparisons to criteria for drinking water and aquatic
life.

Total cadmium (Figure
8) had minimum detectable limits (0.0001 mg/L, 0.0005 mg/L, 0.001 mg/L)
5 to 50 times above the aquatic life criterion (0.00002 mg/L). Suspected preservative
vial contamination occurred between 1986 and 1991, making values during that
time questionable. High cadmium and suspended sediments occurred together
in 1982, 1993 and 1994. This suggests that cadmium was in a particulate form
and probably not biologically available. To evaluate the criteria for aquatic
life accurately, the minimum detectable limit should be lowered to at least
one-tenth of the criterion value, and dissolved cadmium should also be measured
when suspended sediments or turbidity are present.

Total organic carbon (Figure
11) values exceeded the 4 mg/L criterion for drinking water 18% of the
time when non-filterable residue (Figure 32)
was very high. However, all values since 1983 have met this criterion.

Total chromium (Figure
13) had suspected vial contamination between 1986 and 1991 making values
collected during that time questionable. Since then, two values (May 15, 1993
and Aug. 11, 1994) have exceeded the 0.02 mg/L criterion for fish. Also, 86%
of the values were above the 0.002 mg/L criterion for phyto- and zoo-plankton.
High chromium and suspended sediments occurred together in samples from 1993
and 1994. This suggests that chromium was in a particulate form and probably
not biologically available.

Apparent colour (Figure
15) values were highest during the summer and near the minimum detectable
limit (5 units) during the winter. The 100-unit recreation (maximum) criterion
for true colour was met except for three times (July 2 and 9, 1982 and September
26, 1985), and the 15-unit drinking water and recreation criterion was met
at least 40% of the time. However, all criteria are given as true colour values,
where turbidity is removed before measurement. High apparent colour values
occurred in samples with high turbidity, and thus true colour would have been
much lower. True colour should be measured at the site to compare the data
to the criteria effectively.

Total copper (Figure
16) exhibited high values between 1986 and 1991 due to preservative vial
contamination. Seventy-eight percent of the values exceeded the upper (0.004
mg/L) aquatic life criterion, and 89% of the values exceeded the lower (0.002
mg/L) aquatic life criterion outside of the contamination period. High copper
and suspended sediments occurred together. This suggests that copper was in
a particulate form and probably not biologically available. However, copper
exceeded the criteria even when non-filterable residue or turbidity were low,
indicating that the Stikine River had naturally high copper levels. Dissolved
copper should be measured in the future.

Hardness (Figure
18) samples were within the optimum range for drinking water (80-100 mg/L
as CaCO3) 16% of the time. Seventy-nine percent of the values were
below this range, but were still quite acceptable for drinking water. Lowest
hardness values occurred in the summer and highest values occurred in the
winter. Higher flow leads to increased dilution of dissolved constituents
in ground water such as hardness, while lower flow results in less dilution
and higher hardness values.

Total iron (Figure
19) values exceeded the 0.3 mg/L drinking water (aesthetics) and aquatic
life criteria in all but two samples (Feb. 18, 1982 and Feb. 16, 1983). High
values of iron and suspended sediments occurred together in samples collected
between 1982 and 1994. This suggests that iron was in a particulate form and
probably not biologically available. Also, iron would be removed by drinking
water treatment needed to remove turbidity.

Total lead (Figure
20) had suspected vial contamination between 1986 and 1991 making values
collected during that time questionable. Outside of this period, two values
(Aug. 20, 1982 and May 17, 1984) were above the 0.01 mg/L criterion for drinking
water. Also, 9 % of the values exceeded the upper criterion (0.007 mg/L) and
22% exceeded the lower criterion (0.004 mg/L) for aquatic life. High lead
and suspended sediments occurred together in samples collected in 1982, 1984,
1993 and 1994. This suggests that lead was in a particulate form and probably
not biologically available. Also, lead would be removed by drinking water
treatment needed to remove turbidity.

Total manganese (Figure
23) values exceeded the criterion for aquatic life (0.1 mg/L) 44% of the
time and the criterion for drinking water aesthetics (0.05 mg/L) 73% of the
time. High manganese and suspended sediments occurred together between 1982
and 1994. This suggests that manganese was in a particulate form and probably
not biologically available. Also, manganese would be removed by drinking water
treatment needed to remove turbidity.

Total nickel (Figure
25) had one value (May 15, 1993) above the 0.025 mg/L lower criterion
for aquatic life. However, the hardness corresponding to this value (60.6
mg/L) is above the criterion's hardness range, so this value is acceptable.
High nickel values in 1993 and 1994 corresponded to high values of suspended
sediments. This would indicate that the nickel was in a particulate form and
probably not biologically available.

pH (Figure
28) values between 1986 and 1988 were low because of federal laboratory
control problems, and have been omitted. One value (June 16, 1994) was below
the 6.5-unit lower limit for drinking water and aquatic life, but is a probable
error. All other values met criteria.

Non-filterable residue (Figure
32) exceeded the 25 mg/L criterion for good fisheries 82% of the time,
although this criterion may not necessarily apply to mountain and northern
streams. Peak non-filterable residue values corresponded to peak flows. Figure
33 illustrates the relationship between non-filterable residue and flow. Many
water quality indicators reported high values corresponding to high non-filterable
residue. Non-filterable residue and turbidity (Figure 44) had nearly identical
patterns.

Air temperature (Figure
42) values did not drop below 0°C during the winter prior to 1992.
This pattern has been noticed at several of the long-term stations in B.C.
and may be due to a systematic error in measuring or recording air temperature
(Pommen, 1996).

Water temperature (Figure
43) exceeded the 15°C upper aesthetic limit for drinking water and
the lower limit for recreation once (Aug. 17, 1989). This means that the water
was cool enough to be aesthetically pleasing for drinking, but too cold for
water-contact recreation such as swimming.

Turbidity (Figure
44) values exceeded the 50 NTU criterion for recreation 43% of the time.
The 5 NTU aesthetics criterion for drinking water was exceeded 83% of the
time during peak flows, and the 1 NTU health criterion for drinking water
was exceeded 96% of the time. Figure 45 illustrates the relationship between
turbidity and flow. Turbidity removal and disinfection would be needed prior
to drinking.

Total zinc (Figure
47) may have had high values due to preservative vial contamination between
1986 and 1991. Outside that period, 9% of the values were above the 0.03 mg/L
fish and invertebrates criterion. Additionally, 31% of the values exceeded
the 0.015 mg/L algae criterion. High zinc and suspended sediments occurred
together in samples collected during peak flows. This suggests that zinc was
in a particulate form and probably not biologically available.